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cyborg421

Cutting bolts and keeping the thread

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Hi All,

I am about to put castors on my skywatcher scope and will need to be able to cut the bolts and retain the thread. I found this video and thought it might help those doing likewise. :)

Simon

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Small angle grinder, cut bolt, run flat of disc quickly roung at about 45 degrees, quick run around threadform with needle file - game on :)

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Angle grinder?? What's wrong with a bit of hand filing!! (The video method is good BUT it can lead to very fine swarf being left in place which will cut you at the first opportunity!)

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er.. if you've got an angle grinder.:D

Simon

Ohh yeah, very good point ;)

It's not quite kosher anyway's, I was waiting for a string of posts pointing out the dodgyness of using the flat of a cutting disc for grinding ... :):eek:;), officially a big HSE no no, unofficially - a great time saving method of getting a very nice smooth finish :( as practiced by every fab guy I know :p

One thing I don't like about his method though is that it is pretty rough, see at the end, there is ample room for cross threading, much better to file a better lead onto it (with a finer file than he uses) and then whip round the thread form with a needle file - especially with stainless, rough stainless threads bind in an instant and you'll never get them apart without wrecking the bolt.

Cheers :hello2:

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Glad to have generated discussion. It's obviously not perfect but better than hacking the end off and hoping for the best....

Simon

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Glad to have generated discussion. It's obviously not perfect but better than hacking the end off and hoping for the best....

Simon

You're right mate, just about anything is better than that - hang on, using bolt cutters is worse than that. :)

Just go for it, you'll know if it's good when you look at it - enjoy

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I used to cut threads at 45 degrees when on site, never needed any touching up after that.

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Screw a nut onto the bolt before you cut it, once cut screw the nut back off cleaning the threads as it goes...... :-)

Gary

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Was just reading down this and was going to say aa Gary has above :) Nice bit of hand filing first then undo the nut ;)

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Place the bolt in a vice with soft jaws. Now by that i mean a pair of jaws that are made from a softer material than the bolt. At work we normally put abit of ali over the steel jaws, but you could make up a pair of jaws from ali of wood, nylon... anything softer really... Only tighten the vice enought to hold the bolt in place without it moving about, do not over tighten!

Then cut using a hacksaw, using a blade with the right TPI (teeth per inch) high for steel ie 24TPI. slowly cut through the bolt... Let the saw do the work, dont push to hard or rush it.

Then using a smooth file, remove the burr, and create a smooth flat top, and put a small chamfer on the edges, equal to what the bolt origanally looked like.

No need for anything else, espacially grinders, amature :) lol, sorry ;).

Oh and if that does go pear shapes, and you do faf the thread, use a die to cut the thread again...

Hope that helped...

Keiran

Edited by Keiran

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Usually rough cut 'em with a Hacksaw - Or Angle Grinder, if I'm impatient. Remove larger burrs with file, then smooth, by holding vertically, and circular grinding on flat (bench laid) piece of sandpaper. Intrinsic Flexure (eventual fatigue!) of finger & thumb usually create a slightly domed end. ;)

P.S. Angle Grinders do scare the b'jaysus out of me generally though... Fingers are handy(!) things? :)

Edited by Macavity

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Screw a nut onto the bolt before you cut it, once cut screw the nut back off cleaning the threads as it goes...... :-)

That's the way I've always done it.

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Brilliant, everyone has their own tried and trusted methods - it's a bit like making home brew isn't it.

"Let it ferment for a week then p#@@ in it, that's what gives Ye Olde ****** it's unique flavour"

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Well to my mind the guy in the video is a bit of a cowboy :*( Never use a hacksaw horizontaly thats just asking for trouble. Do it like bulldog_keiran said above and you won't be far off mate. Use a die to recut the thread out of choise if you need to but a nut will do if you haven't got one. If I were you I would use a fresh blade in the saw as well. If you "follow" the thread up towards the end that you just cut with a triangular needle file you won't need to even use a nut. :)

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Yes but as stated above how on earth do you control the cut that way.

I have been taught to get square on to the work if possible so the bolt should be horizontal not the hacksaw.

Also he was using the middle of the blade in a sloppy fashion for a blade costing more than a quid.

The whole of the blade sholud be in uses as if its the last one letting the blade do the work like a machine saw with little downward pressure.

I like the 2 nut method as I learned the hard way cutting the bolt without a nut already inboard to help clean then bevel thread end like a new bolt.

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Yes but as stated above how on earth do you control the cut that way.

I have been taught to get square on to the work if possible so the bolt should be horizontal not the hacksaw.

Also he was using the middle of the blade in a sloppy fashion for a blade costing more than a quid.

The whole of the blade sholud be in uses as if its the last one letting the blade do the work like a machine saw with little downward pressure.

I like the 2 nut method as I learned the hard way cutting the bolt without a nut already inboard to help clean then bevel thread end like a new bolt.

You're quite right, One should never use a hacksaw in a horizontal position unless there is no other alternative.

The best and safest way is to place the bolt horizontal with the not-needed part of the thread in the vice end and place a similar bolt or piece of steel the same diameter at the opposite end of the vice jaws and then DO THE VICE UP TIGHT.

You can then use a hacksaw the proper way. This also goes for using a cutoff disk with an angle grinder.

The whole message here is "Always do the vice up tight" the bolt will have a tendancy to move downwards (or sideways if you followed the vid) placing the bit you dont want in the vice means no marks on the bit you did need.

Or if you really want to be safe, you could make some vice keeps with V-grooves in to properly hold round objects.

25 years cutting metal and I've still got all me fingers.

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I think we can safely say that the guy in the video isn't the best.

i think the moral here is not to believe everything you see on u-tube, but hell, if it works for him, who am I to critiscise

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